Blender GPU Support on Linux with AMD Radeon Pro WX 7100 Mobile
By the looks of the lspci you're using the non pro AMD driver which is required for OpenCL at the moment.

The pro driver is available going to AMDs website and searching for drivers for your card. There is a download link for Ubuntu but the latest version they support is Ubuntu 18.04 (x86_64). You might also find you have to use a slightly older kernel version too.

Hopefully at somepoint we will get OpenCL support from the kernel amdgpu driver.

https://www.amd.com/en/support/professional-graphics/radeon-pro/radeon-pro-wx-x100-series/radeon-pro-wx-7100